Explanation: Launched thirty
years ago, NASA's Voyager 1 and 2 spacecraft are now respectively
15 and 12.5 billion kilometers from the Sun,
equivalent to about 14 and 11.5 light-hours distant.
Still functioning, the Voyagers
are being tracked and commanded through the
Deep Space Network.
Having traveled beyond the outer planets, they
are only the third and fourth spacecraft from planet Earth
to escape toward
interstellar space, following in the footsteps of
Pioneer 10 and 11.
A 12-inch gold plated copper disk (a
phonograph
record) containing recorded sounds and images representing human
cultures and life on Earth, is affixed to each Voyager -
a
message in a bottle cast into the cosmic sea.
The recorded material was
selected by a committee chaired by astronomer
Carl Sagan.
Simple diagrams on the cover
symbolically represent
the spacecraft's origin and give instructions for playing the disk.
The exotic construction of the disks should provide them with a long
lifetime as they coast through
interstellar space.